The epidermal growth factor receptor tyrosine kinase (EGFR) is one of the most commonly activated oncoproteins in lung adenocarcinoma, glioblastoma and other cancers. The identification of cancer-associated EGFR mutants, and their predictive power to select patients for treatment with EGFR inhibitors including erlotinib and gefitinib, has led to a major advance in cancer treatment. The collaborative efforts of the Eck and Meyerson laboratories for the past seven years have focused on understanding the structure-function relationship of cancer-derived EGFR mutants with the overarching goal of improved targeted therapies for cancers bearing these mutations. Refinement of our understanding of the mechanisms of action of mutant EGFR, and the spectrum of response of specific mutants to EGFR inhibitors, will permit more efficient development and application of EGFR-directed therapies. In this renewal, we will undertake the following Specific Aims: Aim 1) Characterize the response of novel EGFR mutants, identified by genomic studies, to low- molecular weight ATP-competitive enzymatic inhibitors and to antibody therapies, Aim 2) Perform structural and functional studies of the exon 20 insertion mutants of EGFR, which are resistant to gefitinib, erlotinib and cetuximab, to ascertain potential therapeutic approaches, and Aim 3) Analyze the substrate specificity of wild- type and cancer-derived EGFR mutants through peptide library array experiments, mass spectrometry-based phosphoproteomics, and crystal structure determination. Execution of these aims will help define the pathogenesis of EGFR-driven tumors and will thus provide a critically important mechanistic foundation for clinical trias targeting EGFR in a variety of cancer types using known agents. Additionally, our efforts will structural and mechanistic foundation for development of next-generation EGFR inhibitors that can be effective in patients whose tumors carry EGFR mutants that are resistant to currently available inhibitors. PUBLIC HEALTH RELEVANCE: Mutations in the EGFR gene are a frequent cause of lung cancer, especially in non-smokers. Many different mutations have been identified, and lung cancers cause by some of these EGFR mutations respond to specific drugs such as erlotinib and gefitinib while others do not. The long term goal of our research is to understand why some EGFR mutant cancers are drug resistant, and to lay the foundations for development of drugs to target these resistant tumors.